Integrating A to D Converter
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8-4
Reference
The integrating AD converter must be wired up with an external reference. The prop-
erties of this reference ultimately determine the long-term stability of the unit.
That is why only selected components, which have been tested, and aged, over a long
period of time, are put to use in the 5017.
The reference is composed of a voltage-regulating Z-Diode, heated by a resistor.
Unfortunately, references of this kind have the tendency to drift at the beginning of
their operational life. After an aging process of two months, the most stable compo-
nents are selected and put to use in the 5017. The absolute value of the reference
voltage is of no significance, since the unit is calibrated during production.
